Syntheses and ion-binding properties of cryptands and their polymers

Abstract

Various derivatives of diaza-crown ethers and the polymers containing cryptands were synthesized and their ion-binding properties were investigated by solvent extraction, transport through liquid membrane and conductance measurements. N,N``-Bis(aminoalkyl) derivatives of three different diaza-crown ethers, diaza18-crown-6(DA-18-C-6), DA-15-C-5, and DA-12-C-4, were synthesized via Gabriel synthesis and other substituted diaza-crown ethers including propyl, hydroxyalkyl, and phthalimidoalkyl derivatives were prepared by alkylation with the corresponding bromo compounds. Four different polymers, i.e., polyamide, polyurea, polyimide, and polysulfone, which contain cryptand moiety on their backbones were prepared from the diaza-crown ethers and their aminoalkyl derivatives. Polymers were obtained in 80-100% yield and showed inherent viscosity values in the range of 0.2-0.4 dl/g. In the solvent extractions of picrate salts from aqueous phase into $CH_2Cl_2$ or $CHCl_3$ by cryptands showed that N-alkylated derivatives exhibited enhanced extraction properties compared with their corresponding parent diaza-crown ethers, and phthalimidoalkyl derivatives showed distinct size-selectivity. The most interesting to note was the extremely high but non-selective extraction efficiency of the aminoalkyl derivatives. The polymers prepared by the reaction of DA-18-C-6 and hexamethylene diisocyanate exhibited notably decreased extraction efficiency, and no selectivity towards metal ions was observed. However with the polymers prepared from N-alkylated cryptand moiety the extraction property of the cryptand was retained, even though selectivity was somewhat reduced. Liquid membrane study with water/chloroform/water system indicated that the ion-transport efficiency exhibited by derivatives of cryptands were found to be in accordance with their extraction behavior. However, aminoalkyl derivatives were particular in that very inefficient carrier activity was observed in spite of the...